Comparative Outcomes of Treatment Initiation With Brand vs. Generic Warfarin in Older Patients

Can Generic Medications Be a Safe and Effective Alternative to Brand-Name Drugs for Cardiovascular Disease Treatment? A Systematic Review and Meta-Analysis

Background

Cardiovascular disease is the leading cause of death in most of the world. Previous meta-analyses of generic drugs for the treatment of cardiovascular disease have not provided sufficient evidence to demonstrate the true efficacy and safety of the drugs. Subsequently, concern exists regarding whether the use of generic drugs can fully substitute brand-name drugs in clinical treatment. To enhance the evidence for generic drugs, this meta-analysis compares the actual effectiveness of generic drugs with brand-name drugs in preventing and treating cardiovascular diseases. This study aimed to resolve the controversy over whether generic drugs in cardiovascular disease can replace brand-name drugs, fully evaluating the best evidence on the clinical equivalence of generic drugs.

Methods

The PubMed, Embase, The Cochrane Library, and Clinicaltrials.gov databases were searched. The search period included articles published before December 2023. Studies on generic and branded cardiovascular drugs were collected, and two independent reviewers screened eligibility, extracted study data, and assessed the risk of bias. Safety outcomes included major adverse cardiovascular events and other adverse events. Efficacy outcomes included relevant vital signs (e.g., blood pressure, heart rate, urine volume) and laboratory measures (e.g., international normalized ratio, low-density lipoprotein cholesterol, platelet aggregation inhibition). A meta-analysis and subgroup analysis were conducted using the Rev Man software.

Results

A total of 4238 studies were retrieved, and 87 studies (n = 2,303,818) were included in the qualitative analysis. There were 57 quantitatively assessed studies (n = 560,553), including angiotensin II receptor blockers, beta-blockers, calcium channel blockers, antithrombotic drugs (anticoagulants or antiplatelet agents), diuretics, statins, and other classes of cardiovascular medications. Regarding clinical safety, 19 studies assessed the occurrence of major adverse cardiovascular events (MACEs) (n = 384,640), and 35 reported secondary adverse events (n = 580,125). In addition to the MACEs for statins (risk ratio (RR) 1.13 [1.05, 1.21]) and adverse events (AEs) for calcium channel blockers (RR 0.90 [0.88, 0.91]), there were no significant differences in the overall risk of MACEs (RR = 1.02 [0.90, 1.15]) and minor adverse events (RR = 0.98 [0.91, 1.05]) between generic and brand-name cardiovascular drugs. In terms of effectiveness, there were no significant differences observed between the two groups in blood pressure (BP), platelet aggregation inhibition (PAI), international normalized ratio (INR), low-density lipoprotein (LDL), and urinary sodium levels. Subgroup analyses for the region, study design, duration of follow-up, and grant funding revealed no significant differences in the risk of MACEs. However, the risk of AE was significantly higher in the Asian region for brand-name cardiovascular drugs than for generics. There was no statistically significant difference in risk between generic and brand-name drugs in the remaining subgroup analyses.

Conclusions

Cardiovascular drugs encompass many types; a minority of generic and brand-name drugs have discrepancies. Given the overall development trend of multi-manufacturer generic drugs in the future, this study provides a strong basis for the global application of generic drugs. The feasibility of generic drugs in terms of efficacy and safety in cardiovascular diseases is clarified. However, some drugs still need to be improved to replace the original drugs used in clinical practice completely. Therefore, large-sample, multicenter, high-quality studies are still required to guide the clinical use of cardiovascular drugs.

The PROSPERO registration

CRD42023481597, https://www.crd.york.ac.uk/PROSPERO/view/CRD42023481597.

Narrow Therapeutic Index Drugs: FDA Experience, Views, and Operations

The U.S. Food and Drug Administration (FDA) has defined narrow therapeutic index (NTI) drugs as "those drugs where small differences in dose or blood concentration may lead to serious therapeutic failures and/or adverse drug reactions that are life-threatening or result in persistent or significant disability or incapacity." FDA has undertaken efforts to develop NTI assessment criteria and enhance public confidence in generic NTI drugs through public workshops, research, and post-marketing surveillance. In 2015, FDA formed the NTI Drug Working Group to develop a consistent approach to identify NTI drugs and resolve NTI-related scientific and regulatory issues in a transparent and collaborative manner. One key objective of the NTI Drug Working Group is to evaluate potential NTI drugs based on five general characteristics of NTI drugs as highlighted in the case example for theophylline drug products. As of January 5, 2024, there are 33 drug products, with 14 distinct active ingredients, specified as NTI drugs in their respective product-specific guidances (PSGs) for generic drug development. Future collaborative efforts with other agencies to harmonize the terms and definitions for NTI drugs may help enhance clarity and consistency during the drug development and the regulatory review process.

Comparative Bleeding Risk of Brand Vs Generic Rivaroxaban in Elderly Inpatients with Atrial Fibrillation

Objective

Atrial fibrillation (AF) is the most common abnormal heart rhythm in elderly patients. Rivaroxaban has been widely used for stroke prevention. The anticoagulant response to rivaroxaban increases with age, which may make elderly patients susceptible to adverse outcomes resulting from small differences in bioavailability between generic and brand products.

Methods

We designed a cohort study of ≥65-year-old inpatients with AF. Sociodemographic and laboratory measures of qualified patients who received brand or generic rivaroxaban for at least 72 hours at the study hospital from January 2021 to June 2023 were collected retrospectively. The primary outcome was the incidence of bleeding.

Results

A total of 1008 qualifying patients were included for analysis, with 626 (62.1%) receiving brand rivaroxaban and 382 (37.9%) receiving generic rivaroxaban. After propensity score matching and weighting to account for confounders, the odds ratios comparing brand vs generic rivaroxaban (95% confidence intervals) for the bleeding was 1.15 (0.72-1.82). Results from subgroup analyses of patients with age ≥85, HAS-BLED score ≥ 3, containment of antiplatelet drugs, and female patients were consistent with the primary analysis.

Conclusion

It provides evidence regarding the clinical safety outcome of generic rivaroxaban in the elderly AF population that may be particularly susceptible to adverse outcomes resulting from small allowable differences in pharmacokinetics.

Pharmacokinetics and Generic Drug Switching: A Regulator's View

There appears to be a mismatch between the assumed therapeutic equivalence of generic drugs, their interchangeability, and reported clinical discomfort following generic drug use and drug switches. In this article, we describe why we are of the opinion that the current regulatory approach to the evaluation of generic drugs based on average bioequivalence is sufficient to expect therapeutic equivalence in the clinical setting. This has often been debated, specifically as adverse drug reactions related to generic drug switches are regularly reported. We agree that clinical discomfort during a bioequivalent drug switch may indeed be caused by different exposures to the active substance. However, this difference in exposure is not a result of the characteristics or quality of generic drugs; it is caused by the pharmacokinetic within-subject variability of the active substance, i.e., the variability on the bioavailability of the active substance, when comparing two occasions of administration of the same drug product, to the same patient. Therefore, reported clinical discomfort following generic drug use and drug switches does not warrant a change in the regulatory approach to the evaluation of the bioequivalence of generic drugs. Switching from a brand-name drug to currently approved generic drugs, or between different generic drugs, will in principle result in comparable exposure, within boundaries determined by the within-subject variability of the pharmacokinetics of the active substance involved.